Methods and compositions for coating metal surfaces

ABSTRACT

The invention provides methods and compositions related to adding a coating to a metal surface under low temperature conditions, such as a patina, where a binder is added to the surface, followed by a first dye, optionally the integrity of the first dye layer is disrupted to provide a mottled, cracked appearance, then a second dye layer is added, followed by a clear protective coat.

BACKGROUND OF THE INVENTION

Current methods of coating metal surfaces, e.g., applying a patina to a surface, typically involve heating the surface. This hot patina process is used to create a finished piece that has areas with a textured coloring and areas that are polished metal free of any coloring. The piece will have a clear coat applied as the last step to protect the patinas from wear during normal handling. The process usually involves the following steps, when applied to an investment casting, such as a sculpture or jewelry, or other decorative piece: 1) Prepare investment cast casting according to final look desired, by polishing all areas that will be polished in the final look; roughing up the areas to be patinated as appropriate; cleaning the entire piece, e.g., with a lacquer thinner, and allowing to dry completely; 2) Heat the casting with a torch; 3) Apply chemicals with airbrush, spray bottle or brush to achieve desired results. This may require two or three separate applications of different chemicals to achieve the desired results; 4) Polish the areas that are to have a polished finish, taping the patinated areas if necessary to protect them during the polishing process; 5) Remove the tape; and 6) Either cover the piece with a wax finish or a clear coat spray depending upon the desired result. If wax is used to seal the patina, buff the entire piece with a cloth to achieve the final brilliance. If a clear coat has been used, buff entire piece using fine compounds to achieve final brilliance.

The present process has many disadvantages: heating the piece makes it difficult to handle and makes it difficult to control the process to produce a consistent result from piece to piece. Polishing the piece after patination requires that the patinated surfaces be protected by taping, a labor-intensive and time-consuming process. In general, the process is time-consuming and is highly dependent on the expertise of the operator to produce consistent results. There is a need for an improved process for coating, e.g., patinating, metal surfaces.

SUMMARY OF THE INVENTION

In one aspect the invention provides methods of applying a patina to a metal surface. In certain embodiments, the invention provides a method of applying a patina to a metal surface comprising (i) applying a binder to the area or areas of the metal surface to be patinated, wherein the binder is capable of binding to the metal and to a dye to be used in patination; (ii) allowing the binder to dry; (iii) applying a first dye to the area or areas to be patinated, wherein the first dye adheres to the binder; (iv) allowing the first dye to dry; (v) applying a integrity-breaking substance to the areas coated with the first dye, wherein the integrity-breaking substance causes the first dye coat to lose a smooth appearance; (vi) allowing the area to dry; (vii) applying a second dye coat to the surfaces to be patinated, wherein the second dye adheres to the first dye and to any exposed binder, and wherein the second dye is different from the first dye; (viii) allowing the second dye coat to dry; and (ix) applying a protective coating to the surface. The method may further comprise, after step (viii), removing excess dye from an area or areas to be plain in the final piece. The metal surface may be prepared for patination by (i) determining a patina area or areas on the surface and a plain area or areas on the surface; (ii) for any plain area or areas for which a polish is desired in a final product, polishing the plain area or areas; (iii) cleaning the surface by applying to the surface a surface cleaner; and (iv) allowing surface to dry completely. In certain embodiments there is at least one plain area; in certain embodiments there are a plurality of plain areas, such as at least 2, 3, 4, 5, 6, or more than 6 plain areas. In certain embodiments, the protective coating is allowed to dry completely and the surface is polished to a desired degree of brilliance. In certain embodiments, the metal of the metal surface comprises iron, steel, brass, copper, bronze, silver, gold, or platinum, e.g., silver. The metal surface can be part of a piece of jewelry. In certain embodiments, the piece of jewelry comprises a necklace, pendant, ring, bracelet, charm, or brooch. In certain embodiments, the second dye coat comprises at least 2 different color dyes. In certain embodiments, all the steps are performed at a temperature of less than 50° C. In certain embodiments, the second dye coat has a total thickness between 0.0005 to 0.005 inches. In certain embodiments, the second dye coat has a total thickness between 0.001 and 0.004 inches.

In another aspect the invention provides compositions that include a patinated metal surface. In certain embodiments the invention provides a patinated metal surface comprising (i) a base layer of metal; (ii) a binder bonded to the base metal layer; (iii) a first dye bonded to the binder; (iv) a second dye bonded to the first dye, wherein the second dye is different from the first dye; and (v) a protective coating bonded to the second dye. The patinated surface may further include one or more plain areas that are not patinated. In certain embodiments, the metal comprises iron, steel, brass, copper, bronze, silver, gold, or platinum, e.g., silver. In certain embodiments, the metal surface is part of a piece of jewelry, such as a necklace, pendant, ring, bracelet, or brooch. In certain embodiments, the second dye layer has a thickness between 0.0005 and 0.005 inches. In certain embodiments, the second dye layer has a thickness between 0.001 and 0.004 inches. In certain embodiments, the second dye layer is translucent. In certain embodiments, the patinated metal surface has a mottled, finely cracked appearance.

Incorporation by Reference

All publications, patents, and patent applications mentioned in this specification are herein incorporated by reference to the same extent as if each individual publication, patent, or patent application was specifically and individually indicated to be incorporated by reference.

DETAILED DESCRIPTION OF THE INVENTION

The invention provides methods for applying a coating, such as a patina, to a metal surface, without heating the surface. In certain embodiments, the metal is a precious metal, such as silver, gold, or platinum; in certain embodiments, the metal is cast iron, steel, brass, copper, bronze, silver, gold, or platinum. In preferred embodiments, the metal is silver, including an alloy of silver, e.g., sterling silver. The invention also provides metal surfaces with such a coating. The methods and compositions are useful in any application in which a coating is desired, and are especially useful for decorative patinas in, e.g., sculpture or jewelry. Generally, some parts of the surface are coated while others remain plain, for example, a metallic surface such as a silver surface may have one or more plain areas, which are often highly polished, and one or more areas to which a decorative patina has been applied. For example, the cold patina process can be used to create a finished piece that has areas with a textured coloring and areas that are polished metal free of any coloring.

The invention offers many advantages over traditional methods of applying coatings such as patinas to surfaces, which generally involve heating the surface, applying the patina dye, often with two or three applications to achieve the desired results, polishing areas that are to have a polished finish, taping the patinated areas to protect them during the polishing process, removing the tape, and adding a wax or clear coat, and buffing the piece to achieve a final brilliance. The present invention is advantageous over the traditional patina process in that: 1) It eliminates the time required to heat the piece so that patina can be applied, and allows much easier handling of the pieces during the process since there is no risk of the piece burning the operator's fingers. 2) It allows polishing to be done before any patina is applied. This leads to a much quicker polish time as there is no problem if the polishing goes into the areas that are to be covered in patina later, since the patina can be applied to polished and no-polished areas equally. This means the polishing can be done without worrying about hitting the finished patina. 3) The taping step to protect the patina during polishing is eliminated. Taping is very time consuming as the tape needs to be applied very carefully to the border areas, which can be irregular in shape. 4) There can be significant improvements in quality because the patina can be applied cold instead of hot. Hot patina techniques require heating the metal, which is imprecise because there is no standard or simple method of measuring the temperature of the surface, and because different thicknesses of metal have different temperatures on heating. This leads to variations in the patina from piece to piece. The cold patina process allows for less piece-to-piece variability, since each part of the surface will be the same from place to place and from piece to piece, and is less dependent on the expertise of the operator to produce consistent and high-quality results. In fact, the method may be partially or wholly automated. This still produces pieces with a hand-finished look, because each piece is unique in that the crackle is never the exactly the same from piece to piece. The methods of the invention may be used in any process where a coating, e.g., patina, on a metal surface is desired; they are particularly useful in decorative manufacturing, such as sculptures, jewelry, and the like.

In general, the methods of the invention include applying a coating, e.g., a patina, to a metal surface without heating the surface. The process may be carried out at temperatures below 100° C., for example, below 80, 60, 50 or 40° C., such as at room temperature. Thus, typically the process is carried out at a temperature at which the pieces may be handled without special equipment to protect the operator from heat. This is in contrast to traditional patina processes, which require temperatures in excess of 100° C., and in which the metal pieces cannot be directly handled and, typically, it is not possible to precisely control the heating of the surface, leading to irregularities in the patination and piece-to-piece variation in patina appearance and quality.

In the methods of the present invention, a binder is first applied to the area or areas of the metal surface to be patinated. The binder is a substance, such as a lacquer, that is capable of binding both to the metal and to the dyes that will subsequently be applied. Typically, the binder is a non-dye substance, e.g., a clear substance, so that the further dye layers are not influenced in color by the binder layer. An exemplary binder is Envirobase EC800, PPG Industries, Pittsburgh, Pa., but any suitable binder may be used. It is not necessary to confine the application of binder to the areas to be patinated and, indeed, the preferred method is simply to apply binder, e.g., lacquer, to, generally, the entire metal surface by any suitable method, e.g., spray gun, brush, dipping, and the like. This step may be performed manually or in an automated manner, or a combination of the two. The binder is allowed to dry, which takes 5-20 minutes under normal circumstances; generally after 20 minutes the piece is ready for the next step. It will be appreciated that the purpose of the binder is to provide a strong bond to the metal, on one side, and to the layers of dye that will be applied, on the other side, so that the subsequent patina is strongly bonded to the metal surface. As a result of using the binder, the patina dyes themselves do not come in direct contact with the metal. This is different from the typical patina process, where the dye is bonded directly to the metal, and/or where a chemical reaction, e.g., of the metal, or between the metal and one or more dyes, is involved in the patina process. In the present process, the binder that is typically used keeps the dye physically separated from the metal surface, and, generally, no chemical reaction of the metal, beyond any involved in the adhesion of the binder to the metal, is involved in the patination process.

Then a first dye, which can be considered an undercoat, is applied to the area or areas to be patinated. Some spillover of dye into areas that are to be plain (i.e., metal that is not coated with dye) in the final piece is acceptable, as there can be a later cleanup step to remove such excess. In fact, it is simpler and more efficient to perform the process without regard to precisely depositing the dyes used in the patination area or areas; so long as the entire patination area or areas are covered, excess dye or dyes are easily removed before the final clear coat step, and the removal step is usually easier to control with precision than the application step. In this as well as other ways in the process, taping or other tedious masking procedures may be avoided. Generally the first dye is a base coat, which can be any color; in order to provide a neutral background for application of later dyes, the first dye is often a black dye which is applied as a thin coat. However, it is also possible to use a colored first dye, which imparts a coloring effect on the next coat of dye, as desired. Although the patina process is typically carried out by first applying a binder coat, to which the first dye is then adhered, if the adherence properties of the first dye to the surface to be patinated are sufficiently robust, it is possible in some embodiments to reduce or eliminate the use of the binder before applying the first dye.

In addition, in some processes, e.g., where a pastel effect is desired, two dyes are applied as part of the undercoat process. The first undercoat dye is applied as described above. In the case of a pastel effect, the first dye can be a white dye, or a dye that is predominantly white. Often this first undercoat dye can be an opaque dye (e.g., an opaque white or predominantly white dye), in contrast to subsequent layers, some or all of which are usually translucent. Other colors may be used for the first undercoat layer, depending on the desired effect. The first undercoat dye is allowed to dry, then it is typically coated with a second binder layer, similar or identical to the first binder layer that is used. After the second binder layer has dried, a second undercoat dye is applied and allowed to dry; the second undercoat may be any desired color, and is often black. By using this two-layer approach, the underlying first undercoat layer color, e.g., white, can serve as a background for subsequent colors and leads to an alteration of the subsequent colors, e.g., in the case of a white first undercoat layer, a pastel effect.

Although the patina process could end with the first dye, which could be applied in several coats and/or as several different colors, the surface would be uniform and uninteresting at this point. Thus the process typically includes allowing the base coat of dye to dry (5-20 minutes) then treating the base coat with a substance that disrupts the surface of the first dye, for example to produce an irregular surface appearance, e.g., a mottled, finely cracked appearance. For purposes of description, “first dye” used in this context refers to the upper layer of the undercoat; in some cases, the undercoat will only comprise one layer, in which case the “first dye” refers to this layer; in other cases, as described above, the undercoat will comprise two layers of two different dyes, in which case, the “first dye” is the upper layer (furthest from the surface on which the patina is applied). The step of producing a non-uniform, e.g., mottled or cracked-looking, surface is desirable in decorative applications as it makes the final patina more varied and interesting to the eye; such an effect is often called “crackle.” Any suitable substance may be used, so long as it causes the desired effect of disrupting the smooth appearance of the first dye surface, such as an alcohol, for example, a denatured alcohol such as that supplied by Sunnyside Corporation, Wheeling, Ill. (˜50% Ethyl Alcohol, ˜50% Methyl Alcohol, ˜0.5-1% Methyl Isobutyl Ketone). Without being bound by theory, it is thought that the alcohol or similar substance re-dissolves the first dye and alters the surface tension of the dye layer so that parts of the layer pull together and away from other parts, giving the surface a non-uniform look, e.g., with cracks and/or other irregularities that impart a “depth” to the surface. This effect is thought to be achieved, in the case where alcohol or similar solvent is used, in a purely physical manner, that is, by partial dissolution of the first dye in the solvent (e.g., alcohol), which has a different characteristic than the rest of the dye, e.g., altered surface tension, so that the first dye surface is disrupted in a non-uniform manner. Ultimately this disruption causes each patinated surface that is produced to be unique. If alcohol or a similar solvent is used, no chemical reaction is required to achieve the surface necessary for the final effect; simple dissolution and re-drying is sufficient.

The alcohol or other substance is applied to the base dye in such a way as to contact the dye surface, typically as tiny droplets (though larger droplets may be used if a “drop” effect is desired in the final piece). An ordinary hand mist sprayer may be used and the spray nozzle setting can be adjusted until the desired effect is achieved. It will be appreciated that any suitable method of applying a thin layer of the alcohol or other substance to the first dye layer may be used, so long as the substance is not applied in large enough quantity to cause running and/or excess pooling of the first dye. In certain cases, some pooling or running may be desired to achieve a certain effect, but generally the application of the substance is light enough that this does not occur. The application of the alcohol or other substance may be partly or completely automated; automation can help to achieve repeatable thickness of application of the substance.

The speed of drying of the treated surface after application of the alcohol or other substance can affect the subsequent patina look, with slower drying leading to a coarser look. If a finer look is desired, it can be important to ensure that the drying step is carried out at a high enough temperature, and/or with enough air movement over the piece, so that the alcohol or other substance evaporates at the desired rate. This can be achieved by simply drying in the air if the air temperature is high enough and/or there is enough air movement in the drying facility to achieve the desired effect. Either or both of the temperature and/or air movement can be increased as desired, so as to produce the desired effect on the surface of the first dye; one simple way to do this is to use a hand-held apparatus such as a hand-held hair dryer (blow dryer). For larger operations, the pieces may be placed in a location where air temperature and/or air movement are controlled to such a degree as to achieve the desired effect. For example, air temperature may be controlled so that it is at least 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, or 40° C. during most or all of the drying process, for example, at least 30° C., such as at least 35° C. Additionally, or alternatively, air speed across the surface of the piece may be controlled or monitored so that it is at least 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 mph during most or all of the drying process, for example, at least 2 mph, such as at least 5 mph. It will be appreciated that the heating used in this step, if any, is far below any temperatures used in a hot patina process, and is used only to accelerate evaporation of a solvent, for a period of, typically, no more than a few minutes, e.g., a maximum of 1, 2, 3, 4, 5, 7, 10, 15, 20, 25, 30, 40, or 60 minutes, e.g., no more than 10 minutes, or no more than 5 minutes, or no more than 2 minutes, or no more than one minute. Multiple application and drying steps may be used, e.g., at least 1, 2, 3, 4, or 5 application/dry cycles. The piece may also be gently warmed, as described herein, prior to application of the alcohol or other substance.

After the treated surface has dried, a second dye coat is applied so that the second dye adheres to the first dye and to any exposed binder. For purposes of this description, “second dye” means the dye applied to the previous layer that has been disrupted and rendered non-uniform as described herein; it will be appreciated that, as described herein, this disrupted layer may actually be applied over another dye layer; regardless of whether this is done or not, “second dye” will describe the dye applied to the disrupted, non-uniform dye layer, no matter how many, if any, layers of dye are below it.

The second dye coat is generally the final patina and can be applied in any color or combination of colors, and in as many coats as desired. Any suitable dye may be used for the first and second dye so long as it is capable of adhering to the binder and provides the desired color and look. See, e.g., patina dyes supplied by Sculpt Nouveau. The first and second dyes may be applied by any suitable method that produces the desired coating appearance, such as spray, brush, dabbing, dipping, and the like, or any combination thereof. Preferably, the dyes are applied with an airbrush. Typically coatings are applied manually but in some cases the method may lend itself to automated methods of coating as well as automation of some or all of the other steps of the method, as described here and elsewhere herein. A single coat, or 2, 3, 4, 5, or more than 5 coats may be applied. One color may be used in the second dye coating step, or 2, 3, 4, 5, 6 or more than 6 colors may be used in the second coating step. The second dye coating is allowed to dry (5-20 minutes).

An important aspect of the invention is that the second dye coat is applied over a first dye coat that has been disrupted and rendered non-uniform; in fact, in a basic embodiment the invention encompasses a two-layer composition comprising a first dye layer that is disrupted and non-uniform, wherein the first dye layer adheres directly or indirectly to a surface, such as a metal surface (e.g. a silver or silver alloy surface, such as a sterling silver surface) over which is adhered a second, different dye layer, and methods for producing same. Typically this is done after the first dye coat has dried completely; the look of the patina is not dependent on mingling of the first and second coats and, indeed, this is generally to be avoided, i.e., the second coat is applied on top of a dried first coat and the interaction is primarily or entirely that of adhesion of the second coat to the first coat. This is what gives the patinas of the invention a mottled, cracked look, often called “crackle” in the art. Depending on how the first dye layer is treated, the look can range from a “splash droplet” look to a finely cracked look, reminiscent of porcelain or fine china. Other looks may be achieved, depending on the process used to treat the first dye layer, but patinas of the invention typically provide a non-uniform look, with one or more translucent layers allowing layers below to be seen. In contrast to other patina methods, such looks are accomplished with minimal or no chemical treatment and/or heating, and can be applied to any surface to which the first dye can be made to adhere with sufficient strength to resist scratching and scraping. It will be appreciated that, for simplicity, the process and compositions are described herein as applied to a metal surface, but any suitable surface may be used. For example, in certain embodiments, the patinas are applied on a plastic surface, such as a plastic resin. Such plastics may be used to make solid forms, such as sculptures, for example, animal sculptures, e.g., frog sculptures, and the patinas as described herein applied to the forms by the methods described herein. Thus, the invention encompasses plastic sculptures, e.g., frog sculptures, with a patina as described herein applied to part or all of the surface. Descriptions that are phrased in terms of application to metal are equally applicable to patinas applied to other surfaces, such as plastic surfaces.

The one or more coats of the second dye are generally applied at a thickness that provides a translucent coating, that is, a coating that is not completely opaque but is partially transparent to the layer below. Thus, in certain embodiments the coat or coats of the second dye are applied to a thickness of no greater than than 0.010, 0.009, 0.008, 0.007, 0.006, 0.005, 0.004, 0.003, or 0.002 inches, wherein there is at least some coating on the surface, and/or a thickness of no less than 0.0001, 0.0002, 0.0003, 0.0004, 0.0005, 0.0006, 0.0007, 0.0008, 0.0009, 0.001, or 0.0015 inches, such as between 0.0001 and 0.010 inches, or 0.0005 and 0.007 inches, or 0.0008 and 0.005 inches, or 0.001 and 0.004 inches, or 0.0005 and 0.003 inches, or 0.0008 and 0.002 inches, or 0.001 and 0.003 inches.

Typically, there is also preparation of the surface prior to the patination and further coating and/or other treatment after patination, as well.

Preparation of the surface can include determining which areas of the surface will be patinated and which will remain plain, and bringing the areas to be patinated and to be plain to a suitable finish (e.g., polishing plain areas and ensuring correct roughness for patination for areas to be patinated), and cleaning the surface. In certain embodiments, areas to be patinated are distinguished from plain areas by a difference in the surface, which may achieved, e.g., during casting of the metal piece. For example, an area to be patinated may be recessed or raised relative to an area that is to remain plain. This is especially useful in allowing quick and precise removal of excess dye from areas that are to be plain in the final product, as described more fully below. It will be appreciated that when plain areas of the surface are polished, the polishing step is performed before the patination step, in contrast to traditional patina processes. A typical piece to be patinated can be a cast or otherwise rough piece, for example, a cast sculpture or jewelry piece. It is desirable to have a finish on areas to be patinated of RMS (root mean square, a measure of roughness of surface) of 16-32. Polished areas may be treated to achieve any desired degree of polish, e.g., an RMS of 4-8, or any other desired RMS value as appropriate. Depending on how the piece is made, these values may be achieved by polishing the surface by standard industry methods, or by roughing up areas to be patinated, or a combination thereof. In the case of a cast piece, a raw cast piece can have a surface finish of RMS 125. The entire piece can be polished by standard industry methods to a satin finish, i.e., RMS of 16-32. At that point the areas to be patinated are at the proper finish and no further polishing is done of these areas. Areas for which a higher polish is desired in the final product may be subjected to further polishing, to achieve the desired final polish, e.g., RMS of less than 10, or less than 8, or less than 6, or less than 4, or RMS of 1-10, 2-10, or 2-8, or 3-8, or 4-8. When the proper finish has been achieved in the desired areas, the surface is cleaned to remove dirt, grease, and the like. Any suitable cleaning agent may be used so long as it cleans the surface and does not leave a residue. An exemplary cleaning agent is a lacquer thinner, such as those supplied by Sunnyside Corporation, Wheeling, Ill.

The piece is generally treated after patination to present a finished appearance and to protect the patinated areas. Any patina that has been inadvertently applied to areas that are to be plain in the final product may be removed, using any suitable removal procedure, such as a brush or Q tip and lacquer thinner. Again, this is different from the typical patination process, in which no removal of excess patina is used; in the present process, it is generally part of the overall process to apply excess patina and remove it later, as this is far simpler and more efficient than trying to mask polished areas precisely, a labor-intensive and difficult process. If patinated areas are distinguished physically from plain areas, e.g., recessed or raised relative to plain areas, removal of excess patina is even more efficient, but it is not necessary to physically distinguish areas. After any such removal, the piece is allowed to dry completely.

A protective coating can then be applied to the surface. The protective coating is a transparent coating and protective from ordinary wear and tear; any suitable protective coating may be used, such as Colormaster Acrylic Crystal Clear, from Krylon Products Group. The protective coating is similar or identical to clear coat used to protect finishes on automobiles and the like. The protective coating is allowed to dry completely; the time for drying may be less than 72 hours, less than 48 hours, or less than 36 hours, or less than 24 hours. This is in contrast to typical, e.g., hot patinas, where final drying of a protective coating can take weeks. Finally, if desired, the entire piece is buffed with fine compounds to achieve a final brilliance.

The methods of the invention may be used with any metal surface for which a coating, for example a decorative coating, e.g., patina, is required. Other surfaces, as described herein (e.g., plastic), may also be used, in fact, any surface to which the patina materials will adhere with the requisite strength may be used; for simplicity, the invention is described in terms of embodiments in which a metal surface is patinated. The metal may be any suitable metal, that is, any metal that is capable of bonding to the binding agent. In certain embodiments, the metal is iron, steel, brass, copper, bronze, silver, gold, or platinum. In certain embodiments, the metal is bronze. In certain embodiments, the metal is silver or a silver alloy, such as sterling silver. In certain embodiments, the metal surface is a surface of a piece of jewelry, for example, a piece of silver or silver alloy jewelry such as a pendant, bracelet, ring, earring, necklace, charm, or any other suitable jewelry piece as known in the art.

This cold patina process is used to create a finished piece that has areas with a textured coloring and, typically, areas that are polished metal free of any coloring. Thus, in certain embodiments, the invention provides a composition comprising a metal surface on which are, in order, a binder layer, such as a lacquer layer, a first dye layer, such as a patina dye layer, a second dye layer, such as a second patina dye layer, where the first and second dye layers are different layers, of different colors, and a top protective coating layer that is a clear, non-colored layer. The first dye layer is typically disrupted and non-uniform, that is, treated as described herein to provide a non-uniform surface with easily visible variations, such as striations, cracks, fissures, and the like, in the final patina. The layers are of thicknesses as described herein. In certain embodiments the invention provides a composition comprising a base silver layer bonded to a binder layer, bonded to two different patina layers, with the top patina layer bonded to a protective coating. In certain embodiments the invention provides a composition comprising a base bronze layer bonded to a binder layer, bonded to two different patina layers, with the top patina layer bonded to a protective coating. In certain embodiments the invention provides a composition comprising a base gold layer bonded to a binder layer, bonded to two different patina layers, with the top patina layer bonded to a protective coating. In certain embodiments the invention provides a composition comprising a base platinum layer bonded to a binder layer, bonded to two different patina layers, with the top patina layer bonded to a protective coating. In certain embodiments the invention provides a composition comprising a base stainless steel layer bonded to a binder layer, bonded to two different patina layers, with the top patina layer bonded to a protective coating. In all cases, when a layer is described as a metallic layer, it includes all common alloys of that metal. In all cases, the first patina layer is a non-uniform layer, as described herein.

In certain embodiments the invention provides jewelry, such as jewelry comprising a metal, e.g., steel, or a precious metal, e.g., silver, gold, or platinum, for example, silver, where the jewelry comprises one or more plain areas and one or more patinated areas, and where the patinated area comprises a base layer of binder that is bound to the metal of the jewelry, at least two layers of patina dye that are bound to the binder and/or to each other, and a layer of protective coating bound to the top dye layer. The second layer of patina dye can be translucent, i.e., at a thickness that provides color but not complete opaqueness, such as a thickness as described herein. One or more of the patinated areas can have a mottled, cracked appearance. “Jewelry,” as that term is used herein, includes decorative personal ornaments worn on the person or clothing, and comprising at least one metal surface. Jewelry includes necklaces, pendants, rings of all types, e.g., finger rings, earrings, and other rings, bracelets, brooches, charms, and any other decorative piece worn on the person or clothing.

In certain embodiments, the invention provides a necklace, such as a necklace comprising a metal, e.g., steel, or a precious metal, e.g., silver, gold, or platinum, for example, silver, where the necklace comprises one or more plain areas and one or more patinated areas, and where the patinated area comprises a base layer of binder that is bound to the metal of the necklace, at least two layers of patina dye that are bound to the binder and/or to each other, and a layer of protective coating bound to the top dye layer. Typically one of the patina layers has been treated to provide a non-uniform appearance in the final patina, such as a mottled, cracked, variegated appearance, e.g., “crackle,” as that term is used in the art. The patina layers are of different colors, for example, a base layer comprising a black patina and a second layer that is a colored patina, where the colored patina can be any color that is not black. In some cases, the base layer may also comprise a white or near-white patina. Thicknesses and other aspects of the layers are as described herein.

In certain embodiments, the invention provides a pendant, such as a pendant comprising a metal, e.g., steel, or a precious metal, e.g., silver, gold, or platinum, for example, silver, where the pendant comprises one or more plain areas and one or more patinated areas, and where the patinated area comprises a base layer of binder that is bound to the metal of the pendant, at least two layers of patina dye that are bound to the binder and/or to each other, and a layer of protective coating bound to the top dye layer. Typically one of the patina layers has been treated to provide a non-uniform appearance in the final patina, such as a mottled, cracked, variegated appearance, e.g., “crackle,” as that term is used in the art. The patina layers are of different colors, for example, a base layer comprising a black patina and a second layer that is a colored patina, where the colored patina can be any color that is not black. In some cases, the base layer may also comprise a white or near-white patina. Thicknesses and other aspects of the layers are as described herein.

In certain embodiments, the invention provides a ring, such as a ring comprising a metal, e.g., steel, or a precious metal, e.g., silver, gold, or platinum, for example, silver, where the ring comprises one or more plain areas and one or more patinated areas, and where the patinated area comprises a base layer of binder that is bound to the metal of the ring, at least two layers of patina dye that are bound to the binder and/or to each other, and a layer of protective coating bound to the top dye layer. Typically one of the patina layers has been treated to provide a non-uniform appearance in the final patina, such as a mottled, cracked, variegated appearance, e.g., “crackle,” as that term is used in the art. The patina layers are of different colors, for example, a base layer comprising a black patina and a second layer that is a colored patina, where the colored patina can be any color that is not black. In some cases, the base layer may also comprise a white or near-white patina. Thicknesses and other aspects of the layers are as described herein.

In certain embodiments, the invention provides a bracelet, such as a bracelet comprising a metal, e.g., steel, or a precious metal, e.g., silver, gold, or platinum, for example, silver, where the bracelet comprises one or more plain areas and one or more patinated areas, and where the patinated area comprises a base layer of binder that is bound to the metal of the bracelet, at least two layers of patina dye that are bound to the binder and/or to each other, and a layer of protective coating bound to the top dye layer. Typically one of the patina layers has been treated to provide a non-uniform appearance in the final patina, such as a mottled, cracked, variegated appearance, e.g., “crackle,” as that term is used in the art. The patina layers are of different colors, for example, a base layer comprising a black patina and a second layer that is a colored patina, where the colored patina can be any color that is not black. In some cases, the base layer may also comprise a white or near-white patina. Thicknesses and other aspects of the layers are as described herein.

In certain embodiments, the invention provides a charm, such as a charm comprising a metal, e.g., steel, or a precious metal, e.g., silver, gold, or platinum, for example, silver, where the charm comprises one or more plain areas and one or more patinated areas, and where the patinated area comprises a base layer of binder that is bound to the metal of the charm, at least two layers of patina dye that are bound to the binder and/or to each other, and a layer of protective coating bound to the top dye layer. Typically one of the patina layers has been treated to provide a non-uniform appearance in the final patina, such as a mottled, cracked, variegated appearance, e.g., “crackle,” as that term is used in the art. The patina layers are of different colors, for example, a base layer comprising a black patina and a second layer that is a colored patina, where the colored patina can be any color that is not black. In some cases, the base layer may also comprise a white or near-white patina. Thicknesses and other aspects of the layers are as described herein.

In certain embodiments, the invention provides an earring, such as an earring comprising a metal, e.g., steel, or a precious metal, e.g., silver, gold, or platinum, for example, silver, where the earring comprises one or more plain areas and one or more patinated areas, and where the patinated area comprises a base layer of binder that is bound to the metal of the earring, at least two layers of patina dye that are bound to the binder and/or to each other, and a layer of protective coating bound to the top dye layer. Typically one of the patina layers has been treated to provide a non-uniform appearance in the final patina, such as a mottled, cracked, variegated appearance, e.g., “crackle,” as that term is used in the art. The patina layers are of different colors, for example, a base layer comprising a black patina and a second layer that is a colored patina, where the colored patina can be any color that is not black. In some cases, the base layer may also comprise a white or near-white patina. Thicknesses and other aspects of the layers are as described herein.

While preferred embodiments of the present invention have been shown and described herein, it will be obvious to those skilled in the art that such embodiments are provided by way of example only. Numerous variations, changes, and substitutions will now occur to those skilled in the art without departing from the invention. It should be understood that various alternatives to the embodiments of the invention described herein may be employed in practicing the invention. It is intended that the following claims define the scope of the invention and that methods and structures within the scope of these claims and their equivalents be covered thereby. 

What is claimed is:
 1. A method of applying a patina to a metal surface comprising (i) applying a binder to the area or areas of the metal surface to be patinated, wherein the binder is capable of binding to the metal and to a dye to be used in patination; (ii) allowing the binder to dry; (iii) applying a first dye to the area or areas to be patinated, wherein the first dye adheres to the binder; (iv) allowing the first dye to dry; (v) applying a integrity-breaking substance to the areas coated with the first dye, wherein the integrity-breaking substance causes the first dye coat to lose a smooth appearance; (vi) allowing the area to dry; (vii) applying a second dye coat to the surfaces to be patinated, wherein the second dye adheres to the first dye and to any exposed binder, and wherein the second dye is different from the first dye; (viii) allowing the second dye coat to dry; and (ix) applying a protective coating to the surface.
 2. The method of claim 1 further comprising, after step (viii), removing excess dye from an area or areas to be plain in the final piece.
 3. The method of claim 1 wherein the metal surface is prepared for patination by (i) determining a patina area or areas on the surface and a plain area or areas on the surface; (ii) for any plain area or areas for which a polish is desired in a final product, polishing the plain area or areas; (iii) cleaning the surface by applying to the surface a surface cleaner; and (iv) allowing surface to dry completely.
 4. The method of claim 1 wherein the protective coating is allowed to dry completely and the surface is polished to a desired degree of brilliance.
 5. The method of claim 1 wherein the metal of the metal surface comprises iron, steel, brass, copper, bronze, silver, gold, or platinum.
 6. The method of claim 1 wherein the metal of the metal surface comprises silver.
 7. The method of claim 1 wherein the metal surface is part of a piece of jewelry.
 8. The method of claim 1 wherein the jewelry comprises a necklace, pendant, ring, bracelet, or brooch.
 9. The method of claim 1 wherein the second dye coat comprises at least 2 different color dyes.
 10. The method of claim 1 wherein all the steps are performed at a temperature of less than 50° C.
 11. The method of claim 1 wherein the second dye coat has a total thickness between 0.0005 to 0.005 inches.
 12. The method of claim 1 wherein the second dye coat has a total thickness between 0.001 and 0.004 inches.
 13. A patinated metal surface comprising (i) a base layer of metal; (ii) a binder bonded to the base metal layer; (iii) a first dye bonded to the binder; (iv) a second dye bonded to the first dye, wherein the second dye is different from the first dye; and (v) a protective coating bonded to the second dye.
 14. The patinated metal surface of claim 13 further comprising one or more plain areas that are not patinated.
 15. The patinated metal surface of claim 13 wherein the metal comprises iron, steel, brass, copper, bronze, silver, gold, or platinum.
 16. The patinated metal surface of claim 15 wherein the metal of the metal surface comprises silver.
 17. The patinated metal surface of claim 13 wherein the metal surface is part of a piece of jewelry.
 18. The patinated metal surface of claim 17 wherein the jewelry comprises a necklace, pendant, ring, bracelet, or brooch.
 19. The patinated metal surface of claim 13 wherein the second dye layer has a thickness between 0.0005 and 0.005 inches.
 20. The patinated metal surface of claim 19 wherein the second dye layer has a thickness between 0.001 and 0.004 inches.
 21. The patinated metal surface of claim 13 wherein the second dye layer is translucent.
 22. The patinated metal surface of claim 13 wherein the patinated metal surface has a mottled, finely cracked appearance. 